The ethyl acetate extracts through maceration extraction of stem bark of Glossonema boveanum (Decne.) (Asclepiadaceae) afforded one pentacyclic triterpene, betulinic acid, which is reported for the first time in this plant. The structure of the isolated compound was identified on the basis of 1D NMR (1H, 13C and DEPT), 2D NMR (COSY, HSQC, HMBC and NOESY) and by comparison with reported data. The isolated compound was then tested for its antibacterial activity against two human Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and three Gram-negative bacteria (Salmonella typhi, Shigella dysenteriae and Escherichia coli) and was found to be effective against all these species. The result of the minimum inhibitory concentration (MIC) revealed that betulinic acid inhibits the growth of the tested microorganisms and was as low as 3.125 µg/ml.

Keywords: Glossonema boveanum, betulinic acid, antibacterial activity.